/*
** $Id: lua.c,v 1.230.1.1 2017/04/19 17:29:57 roberto Exp $
** Lua stand-alone interpreter
** See Copyright Notice in lua.h
*/

#define lua_c

#include "lprefix.h"

#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "lua.h"

#include "lauxlib.h"
#include "lualib.h"

#if !defined(LUA_PROMPT)
#define LUA_PROMPT "> "
#define LUA_PROMPT2 ">> "
#endif

#if !defined(LUA_PROGNAME)
#define LUA_PROGNAME "lua"
#endif

#if !defined(LUA_MAXINPUT)
#define LUA_MAXINPUT 512
#endif

#if !defined(LUA_INIT_VAR)
#define LUA_INIT_VAR "LUA_INIT"
#endif

#define LUA_INITVARVERSION LUA_INIT_VAR LUA_VERSUFFIX

/*
** lua_stdin_is_tty detects whether the standard input is a 'tty' (that
** is, whether we're running lua interactively).
*/
#if !defined(lua_stdin_is_tty) /* { */

#if defined(LUA_USE_POSIX) /* { */

#include <unistd.h>
#define lua_stdin_is_tty() isatty(0)

#elif defined(LUA_USE_WINDOWS) /* }{ */

#include <io.h>
#include <windows.h>

#define lua_stdin_is_tty() _isatty(_fileno(stdin))

#else                        /* }{ */

/* ISO C definition */
#define lua_stdin_is_tty() 1 /* assume stdin is a tty */

#endif /* } */

#endif /* } */

/*
** lua_readline defines how to show a prompt and then read a line from
** the standard input.
** lua_saveline defines how to "save" a read line in a "history".
** lua_freeline defines how to free a line read by lua_readline.
*/
#if !defined(lua_readline) /* { */

#if defined(LUA_USE_READLINE) /* { */

#include <readline/readline.h>
#include <readline/history.h>
#define lua_readline(L, b, p) ((void)L, ((b) = readline(p)) != NULL)
#define lua_saveline(L, line) ((void)L, add_history(line))
#define lua_freeline(L, b) ((void)L, free(b))

#else /* }{ */

#define lua_readline(L, b, p)                                 \
    ((void)L,                                                 \
     fputs(p, stdout),                                        \
     fflush(stdout),                        /* show prompt */ \
     fgets(b, LUA_MAXINPUT, stdin) != NULL) /* get line */
#define lua_saveline(L, line) \
    {                         \
        (void)L;              \
        (void)line;           \
    }
#define lua_freeline(L, b) \
    {                      \
        (void)L;           \
        (void)b;           \
    }

#endif /* } */

#endif /* } */

static lua_State* globalL = NULL;

static const char* progname = LUA_PROGNAME;

/*
** Hook set by signal function to stop the interpreter.
*/
static void lstop(lua_State* L, lua_Debug* ar)
{
    (void)ar;                   /* unused arg. */
    lua_sethook(L, NULL, 0, 0); /* reset hook */
    luaL_error(L, "interrupted!");
}

/*
** Function to be called at a C signal. Because a C signal cannot
** just change a Lua state (as there is no proper synchronization),
** this function only sets a hook that, when called, will stop the
** interpreter.
*/
static void laction(int i)
{
    signal(i, SIG_DFL); /* if another SIGINT happens, terminate process */
    lua_sethook(globalL, lstop, LUA_MASKCALL | LUA_MASKRET | LUA_MASKCOUNT, 1);
}

static void print_usage(const char* badoption)
{
    lua_writestringerror("%s: ", progname);
    if (badoption[1] == 'e' || badoption[1] == 'l')
        lua_writestringerror("'%s' needs argument\n", badoption);
    else
        lua_writestringerror("unrecognized option '%s'\n", badoption);
    lua_writestringerror("usage: %s [options] [script [args]]\n"
                         "Available options are:\n"
                         "  -e stat  execute string 'stat'\n"
                         "  -i       enter interactive mode after executing 'script'\n"
                         "  -l name  require library 'name' into global 'name'\n"
                         "  -v       show version information\n"
                         "  -E       ignore environment variables\n"
                         "  --       stop handling options\n"
                         "  -        stop handling options and execute stdin\n",
                         progname);
}

/*
** Prints an error message, adding the program name in front of it
** (if present)
*/
static void l_message(const char* pname, const char* msg)
{
    if (pname)
        lua_writestringerror("%s: ", pname);
    lua_writestringerror("%s\n", msg);
}

/*
** Check whether 'status' is not OK and, if so, prints the error
** message on the top of the stack. It assumes that the error object
** is a string, as it was either generated by Lua or by 'msghandler'.
*/
static int report(lua_State* L, int status)
{
    if (status != LUA_OK)
    {
        const char* msg = lua_tostring(L, -1);
        l_message(progname, msg);
        lua_pop(L, 1); /* remove message */
    }
    return status;
}

/*
** Message handler used to run all chunks
*/
static int msghandler(lua_State* L)
{
    const char* msg = lua_tostring(L, 1);
    if (msg == NULL)
    {                                            /* is error object not a string? */
        if (luaL_callmeta(L, 1, "__tostring") && /* does it have a metamethod */
            lua_type(L, -1) == LUA_TSTRING)      /* that produces a string? */
            return 1;                            /* that is the message */
        else
            msg = lua_pushfstring(L, "(error object is a %s value)", luaL_typename(L, 1));
    }
    luaL_traceback(L, L, msg, 1); /* append a standard traceback */
    return 1;                     /* return the traceback */
}

/*
** Interface to 'lua_pcall', which sets appropriate message function
** and C-signal handler. Used to run all chunks.
*/
static int docall(lua_State* L, int narg, int nres)
{
    int status;
    int base = lua_gettop(L) - narg;  /* function index */
    lua_pushcfunction(L, msghandler); /* push message handler */
    lua_insert(L, base);              /* put it under function and args */
    globalL = L;                      /* to be available to 'laction' */
    signal(SIGINT, laction);          /* set C-signal handler */
    status = lua_pcall(L, narg, nres, base);
    signal(SIGINT, SIG_DFL); /* reset C-signal handler */
    lua_remove(L, base);     /* remove message handler from the stack */
    return status;
}

static void print_version(void)
{
    lua_writestring(LUA_COPYRIGHT, strlen(LUA_COPYRIGHT));
    lua_writeline();
}

/*
** Create the 'arg' table, which stores all arguments from the
** command line ('argv'). It should be aligned so that, at index 0,
** it has 'argv[script]', which is the script name. The arguments
** to the script (everything after 'script') go to positive indices;
** other arguments (before the script name) go to negative indices.
** If there is no script name, assume interpreter's name as base.
*/
static void createargtable(lua_State* L, char** argv, int argc, int script)
{
    int i, narg;
    if (script == argc)
        script = 0;             /* no script name? */
    narg = argc - (script + 1); /* number of positive indices */
    lua_createtable(L, narg, script + 1);
    for (i = 0; i < argc; i++)
    {
        lua_pushstring(L, argv[i]);
        lua_rawseti(L, -2, i - script);
    }
    lua_setglobal(L, "arg");
}

static int dochunk(lua_State* L, int status)
{
    if (status == LUA_OK)
        status = docall(L, 0, 0);
    return report(L, status);
}

static int dofile(lua_State* L, const char* name) { return dochunk(L, luaL_loadfile(L, name)); }

static int dostring(lua_State* L, const char* s, const char* name) { return dochunk(L, luaL_loadbuffer(L, s, strlen(s), name)); }

/*
** Calls 'require(name)' and stores the result in a global variable
** with the given name.
*/
static int dolibrary(lua_State* L, const char* name)
{
    int status;
    lua_getglobal(L, "require");
    lua_pushstring(L, name);
    status = docall(L, 1, 1); /* call 'require(name)' */
    if (status == LUA_OK)
        lua_setglobal(L, name); /* global[name] = require return */
    return report(L, status);
}

/*
** Returns the string to be used as a prompt by the interpreter.
*/
static const char* get_prompt(lua_State* L, int firstline)
{
    const char* p;
    lua_getglobal(L, firstline ? "_PROMPT" : "_PROMPT2");
    p = lua_tostring(L, -1);
    if (p == NULL)
        p = (firstline ? LUA_PROMPT : LUA_PROMPT2);
    return p;
}

/* mark in error messages for incomplete statements */
#define EOFMARK "<eof>"
#define marklen (sizeof(EOFMARK) / sizeof(char) - 1)

/*
** Check whether 'status' signals a syntax error and the error
** message at the top of the stack ends with the above mark for
** incomplete statements.
*/
static int incomplete(lua_State* L, int status)
{
    if (status == LUA_ERRSYNTAX)
    {
        size_t lmsg;
        const char* msg = lua_tolstring(L, -1, &lmsg);
        if (lmsg >= marklen && strcmp(msg + lmsg - marklen, EOFMARK) == 0)
        {
            lua_pop(L, 1);
            return 1;
        }
    }
    return 0; /* else... */
}

/*
** Prompt the user, read a line, and push it into the Lua stack.
*/
static int pushline(lua_State* L, int firstline)
{
    char buffer[LUA_MAXINPUT];
    char* b = buffer;
    size_t l;
    const char* prmt = get_prompt(L, firstline);
    int readstatus = lua_readline(L, b, prmt);
    if (readstatus == 0)
        return 0;  /* no input (prompt will be popped by caller) */
    lua_pop(L, 1); /* remove prompt */
    l = strlen(b);
    if (l > 0 && b[l - 1] == '\n')              /* line ends with newline? */
        b[--l] = '\0';                          /* remove it */
    if (firstline && b[0] == '=')               /* for compatibility with 5.2, ... */
        lua_pushfstring(L, "return %s", b + 1); /* change '=' to 'return' */
    else
        lua_pushlstring(L, b, l);
    lua_freeline(L, b);
    return 1;
}

/*
** Try to compile line on the stack as 'return <line>;'; on return, stack
** has either compiled chunk or original line (if compilation failed).
*/
static int addreturn(lua_State* L)
{
    const char* line = lua_tostring(L, -1); /* original line */
    const char* retline = lua_pushfstring(L, "return %s;", line);
    int status = luaL_loadbuffer(L, retline, strlen(retline), "=stdin");
    if (status == LUA_OK)
    {
        lua_remove(L, -2);         /* remove modified line */
        if (line[0] != '\0')       /* non empty? */
            lua_saveline(L, line); /* keep history */
    }
    else
        lua_pop(L, 2); /* pop result from 'luaL_loadbuffer' and modified line */
    return status;
}

/*
** Read multiple lines until a complete Lua statement
*/
static int multiline(lua_State* L)
{
    for (;;)
    { /* repeat until gets a complete statement */
        size_t len;
        const char* line = lua_tolstring(L, 1, &len);         /* get what it has */
        int status = luaL_loadbuffer(L, line, len, "=stdin"); /* try it */
        if (!incomplete(L, status) || !pushline(L, 0))
        {
            lua_saveline(L, line); /* keep history */
            return status;         /* cannot or should not try to add continuation line */
        }
        lua_pushliteral(L, "\n"); /* add newline... */
        lua_insert(L, -2);        /* ...between the two lines */
        lua_concat(L, 3);         /* join them */
    }
}

/*
** Read a line and try to load (compile) it first as an expression (by
** adding "return " in front of it) and second as a statement. Return
** the final status of load/call with the resulting function (if any)
** in the top of the stack.
*/
static int loadline(lua_State* L)
{
    int status;
    lua_settop(L, 0);
    if (!pushline(L, 1))
        return -1;                         /* no input */
    if ((status = addreturn(L)) != LUA_OK) /* 'return ...' did not work? */
        status = multiline(L);             /* try as command, maybe with continuation lines */
    lua_remove(L, 1);                      /* remove line from the stack */
    lua_assert(lua_gettop(L) == 1);
    return status;
}

/*
** Prints (calling the Lua 'print' function) any values on the stack
*/
static void l_print(lua_State* L)
{
    int n = lua_gettop(L);
    if (n > 0)
    { /* any result to be printed? */
        luaL_checkstack(L, LUA_MINSTACK, "too many results to print");
        lua_getglobal(L, "print");
        lua_insert(L, 1);
        if (lua_pcall(L, n, 0, 0) != LUA_OK)
            l_message(progname, lua_pushfstring(L, "error calling 'print' (%s)", lua_tostring(L, -1)));
    }
}

/*
** Do the REPL: repeatedly read (load) a line, evaluate (call) it, and
** print any results.
*/
static void doREPL(lua_State* L)
{
    int status;
    const char* oldprogname = progname;
    progname = NULL; /* no 'progname' on errors in interactive mode */
    while ((status = loadline(L)) != -1)
    {
        if (status == LUA_OK)
            status = docall(L, 0, LUA_MULTRET);
        if (status == LUA_OK)
            l_print(L);
        else
            report(L, status);
    }
    lua_settop(L, 0); /* clear stack */
    lua_writeline();
    progname = oldprogname;
}

/*
** Push on the stack the contents of table 'arg' from 1 to #arg
*/
static int pushargs(lua_State* L)
{
    int i, n;
    if (lua_getglobal(L, "arg") != LUA_TTABLE)
        luaL_error(L, "'arg' is not a table");
    n = (int)luaL_len(L, -1);
    luaL_checkstack(L, n + 3, "too many arguments to script");
    for (i = 1; i <= n; i++) lua_rawgeti(L, -i, i);
    lua_remove(L, -i); /* remove table from the stack */
    return n;
}

static int handle_script(lua_State* L, char** argv)
{
    int status;
    const char* fname = argv[0];
    if (strcmp(fname, "-") == 0 && strcmp(argv[-1], "--") != 0)
        fname = NULL; /* stdin */
    status = luaL_loadfile(L, fname);
    if (status == LUA_OK)
    {
        int n = pushargs(L); /* push arguments to script */
        status = docall(L, n, LUA_MULTRET);
    }
    return report(L, status);
}

/* bits of various argument indicators in 'args' */
#define has_error 1 /* bad option */
#define has_i 2     /* -i */
#define has_v 4     /* -v */
#define has_e 8     /* -e */
#define has_E 16    /* -E */

/*
** Traverses all arguments from 'argv', returning a mask with those
** needed before running any Lua code (or an error code if it finds
** any invalid argument). 'first' returns the first not-handled argument
** (either the script name or a bad argument in case of error).
*/
static int collectargs(char** argv, int* first)
{
    int args = 0;
    int i;
    for (i = 1; argv[i] != NULL; i++)
    {
        *first = i;
        if (argv[i][0] != '-') /* not an option? */
            return args;       /* stop handling options */
        switch (argv[i][1])
        {                           /* else check option */
        case '-':                   /* '--' */
            if (argv[i][2] != '\0') /* extra characters after '--'? */
                return has_error;   /* invalid option */
            *first = i + 1;
            return args;
        case '\0':       /* '-' */
            return args; /* script "name" is '-' */
        case 'E':
            if (argv[i][2] != '\0') /* extra characters after 1st? */
                return has_error;   /* invalid option */
            args |= has_E;
            break;
        case 'i':
            args |= has_i; /* (-i implies -v) */ /* FALLTHROUGH */
        case 'v':
            if (argv[i][2] != '\0') /* extra characters after 1st? */
                return has_error;   /* invalid option */
            args |= has_v;
            break;
        case 'e':
            args |= has_e; /* FALLTHROUGH */
        case 'l':          /* both options need an argument */
            if (argv[i][2] == '\0')
            {        /* no concatenated argument? */
                i++; /* try next 'argv' */
                if (argv[i] == NULL || argv[i][0] == '-')
                    return has_error; /* no next argument or it is another option */
            }
            break;
        default: /* invalid option */
            return has_error;
        }
    }
    *first = i; /* no script name */
    return args;
}

/*
** Processes options 'e' and 'l', which involve running Lua code.
** Returns 0 if some code raises an error.
*/
static int runargs(lua_State* L, char** argv, int n)
{
    int i;
    for (i = 1; i < n; i++)
    {
        int option = argv[i][1];
        lua_assert(argv[i][0] == '-'); /* already checked */
        if (option == 'e' || option == 'l')
        {
            int status;
            const char* extra = argv[i] + 2; /* both options need an argument */
            if (*extra == '\0')
                extra = argv[++i];
            lua_assert(extra != NULL);
            status = (option == 'e') ? dostring(L, extra, "=(command line)") : dolibrary(L, extra);
            if (status != LUA_OK)
                return 0;
        }
    }
    return 1;
}

static int handle_luainit(lua_State* L)
{
    const char* name = "=" LUA_INITVARVERSION;
    const char* init = getenv(name + 1);
    if (init == NULL)
    {
        name = "=" LUA_INIT_VAR;
        init = getenv(name + 1); /* try alternative name */
    }
    if (init == NULL)
        return LUA_OK;
    else if (init[0] == '@')
        return dofile(L, init + 1);
    else
        return dostring(L, init, name);
}

/*
** Main body of stand-alone interpreter (to be called in protected mode).
** Reads the options and handles them all.
*/
static int pmain(lua_State* L)
{
    int argc = (int)lua_tointeger(L, 1);
    char** argv = (char**)lua_touserdata(L, 2);
    int script;
    int args = collectargs(argv, &script);
    luaL_checkversion(L); /* check that interpreter has correct version */
    if (argv[0] && argv[0][0])
        progname = argv[0];
    if (args == has_error)
    {                              /* bad arg? */
        print_usage(argv[script]); /* 'script' has index of bad arg. */
        return 0;
    }
    if (args & has_v) /* option '-v'? */
        print_version();
    if (args & has_E)
    {                          /* option '-E'? */
        lua_pushboolean(L, 1); /* signal for libraries to ignore env. vars. */
        lua_setfield(L, LUA_REGISTRYINDEX, "LUA_NOENV");
    }
    luaL_openlibs(L);                      /* open standard libraries */
    createargtable(L, argv, argc, script); /* create table 'arg' */
    if (!(args & has_E))
    {                                    /* no option '-E'? */
        if (handle_luainit(L) != LUA_OK) /* run LUA_INIT */
            return 0;                    /* error running LUA_INIT */
    }
    if (!runargs(L, argv, script)) /* execute arguments -e and -l */
        return 0;                  /* something failed */
    if (script < argc &&           /* execute main script (if there is one) */
        handle_script(L, argv + script) != LUA_OK)
        return 0;
    if (args & has_i) /* -i option? */
        doREPL(L);    /* do read-eval-print loop */
    else if (script == argc && !(args & (has_e | has_v)))
    { /* no arguments? */
        if (lua_stdin_is_tty())
        { /* running in interactive mode? */
            print_version();
            doREPL(L); /* do read-eval-print loop */
        }
        else
            dofile(L, NULL); /* executes stdin as a file */
    }
    lua_pushboolean(L, 1); /* signal no errors */
    return 1;
}

int main(int argc, char** argv)
{
    int status, result;
    lua_State* L = luaL_newstate(); /* create state */
    if (L == NULL)
    {
        l_message(argv[0], "cannot create state: not enough memory");
        return EXIT_FAILURE;
    }
    lua_pushcfunction(L, &pmain);   /* to call 'pmain' in protected mode */
    lua_pushinteger(L, argc);       /* 1st argument */
    lua_pushlightuserdata(L, argv); /* 2nd argument */
    status = lua_pcall(L, 2, 1, 0); /* do the call */
    result = lua_toboolean(L, -1);  /* get result */
    report(L, status);
    lua_close(L);
    return (result && status == LUA_OK) ? EXIT_SUCCESS : EXIT_FAILURE;
}
